Entrepreneur and venture capitalist David Goldberg, the husband of Facebook COO Sheryl Sandberg, died suddenly last night. He was 47.

The news was confirmed by his brother, Robert, in a Facebook post. "It's with incredible shock and sadness that I'm letting our friends and family know that my amazing brother, Dave Goldberg, beloved husband of Sheryl Sandberg, father of two wonderful children, and son of Paula Goldberg, passed away suddenly last night,” he wrote.

The cause of his death is not yet known.

For the last six years, Goldberg served as CEO of Palo Alto, Calif.-based online survey maker SurveyMonkey. A Harvard grad, Goldberg began his career as a consultant and then worked as a director of marketing at Capitol Records before founding Launch Media, an online music company he sold to Yahoo in 2001. Goldberg went on to run Yahoo Music, founded another music startup called Dashbox and served as Entrepreneur in Residence at Benchmark Capital. He also sat on the boards of Graham Holdings (formerly The Washington Post Co.) and FilmTrack after it bought Dashbox this past November.

A veritable Silicon Valley power couple, Goldberg and Sandberg met in 1996 while they were both working in Los Angeles and began dating six years later. They married in April 2004 and had two children.

In her 2013 best-selling book Lean In, Sandberg said she owed much of her success to her husband and the strong foundation they had created together. Goldberg echoed similar thoughts in an LA Times interview published that same year: “On the day–to-day stuff we both ask each other for advice. But it is great having one of the smartest people in business as your partner. I don’t have to make an appointment to ask what you think about this or whatever, it’s good with my team. I always say, 'Well Sheryl said.' "

News of his death rippled across the tech world. In a Facebook post, Facebook founder Mark Zuckerberg wrote, “Dave Goldberg was an amazing person and I am glad I got to know him. My thoughts and prayers are with Sheryl and her family.”

Twitter CEO Dick Costolo, journalist Katie Couric and media guru Arianna Huffington were among the many to chime in.